The colors produced by color printers can vary as a function of media type, ink, print heads, temperature, humidity, etc. To address color variation, color characterization instruments (e.g., spectrophotometers) and device characterization profiling tools (e.g. International Color Consortium (ICC) profiles) for devices such as printers may be created. Device characterization profiling facilitates proper color handling.
In order to create a printer color profile, a printing system may print a test color pattern. For example, a test color pattern may be printed including a plurality of color patches arranged in a predetermined pattern. A color measurement device (e.g., a spectrophotometer or a colorimeter) may scan the test color pattern, and the color measurements may be used to create a profile for the printer that can be used to insure printing colors in a consistent manner.
There is a variety of methods for analyzing colors printed on a substrate. Such methods include, for example, using a hand-held spectrophotometer including a wheel that contacts the color patches on the paper. The wheel is for maintaining a desired spatial relationship between the spectrophotometer and the paper. As the spectrophotometer is moved, the wheel measures the speed and direction of the movement while the spectrophotometer determines color on locations across the substrate.
In some other methods, a color sensor (e.g., a spectrophotometer or a colorimeter) is mounted in the paper path of the moving sheets in a printer to provide color measurements of the test color patches printed on the sheets as they pass the color measurement device. In such color analysis methods, the color sensor does not contact the paper. However, color sensors may be sensitive to sensor-to-substrate distance. Hence, factors such as variations in a paper's position or differences in media thickness may reduce color analysis accuracy. Some methods include adjusting the color sensor output for taking into account variations in the vertical position of substrate locations on which color is measured.